Rare earth flouride lubricant for die casting components

ABSTRACT

A rare earth halide preferably a rare earth fluoride such as cerium tri-fluoride or lanthanum tri-fluoride is used as a lubricant for die casting components.

Umted States Patent 11 1 1111 3,830,280

Larsen Aug. 20, 1974 [54] RARE EARTH FLOURIDE LUBRICANT FOR 3,081,196 3/1963 MacDonald 252/12 DIE CASTING COMPONENTS 3,372,113 3/1968 3,411,564 11/1968 [75] Inventor: Earl I. Larsen, lndlanapolrs, 1nd. 3 419 110 2 9 3 [73] Assignee: P. R. Mallory & Co. Inc., lnd1anapo11s, 1nd. 471944 W973 221 Filed; Jam 25 97 3,756,925 9/1973 Takeuchi el al. 252/12.2

[ PP NOJ 109,594 Primary Examiner-Daniel E. Wyman Assistant Examinerl. Vaughn 52 U.S. Cl. 164/72, 252/25 Mame)" "0mm; 51 1111. c1 822d 17/00, ClOm 7/02 Robe" Meyer [58] Field of Search 252/25; 164/72 [57] ABSTRACT [56] References Cited A rare earth halide preferably a rare earth fluoride UNITED STATES PATENTS such as cerium tri-fluoride 0r lanthanum tri-fluoride is 2 236 728 4/1941 Given 148/6 35 used as a lubricant for die casting components. 2:700:623 1 1955 Hall 252/12 3 Claims, No Drawings RARE EARTH FLOURIDE LUBRICANT FORDIE CASTING COMPONENTS BACKGROUND When manufacturing metallic articles, and more specifically die castings by the die casting process wherein molten metals and alloys are forced under pressure into cavities of the desired geometry, it is necessary to use a so-called mold release so that the casting can be stripped or ejected from the die casting mold. In addition to acting as a mold release, the lubricant also prevents the molten metal or alloy from eroding the die, core rods, sprue, or other shaping member, and also prevents the molten metal or alloy from wetting the die and its component parts. This is presently accomplished by coating the die cavity, core rods and other shaping member parts of the dies with some type of lubricant.

In some operations, for example brass die castings, it is necessary to coat the working surfaces for each casting or shot. Many die casters use colloidal graphite or grease thinned with a vehicle such as kerosene. This results in the generation of smoke which causes air pollutlon.

To overcome the latter condition, attempts have been made to use water base lubricants. However, water base lubricants cause checking and'cracking in the surface of brass castings.

Another problem that arises from the use of the foregoing lubricants is that the carrier vehicle such'as kerosene or water is decomposed or vaporized by the temperature of the molten metal or alloy being cast. This leaves a carbonaceous film on the working surfaces of the die and other shaping member components. As the carbonaceous film builds up and gets thicker with repeated applications of thelubricant', it is necessary to stop the operation, open up the dies, and mechanically clean away the accumulated deposit. Otherwise, outof-tolerance castings result. I

Thick lubricant deposits also prevent rapid heat flow from the solidifying casting into the die material which can cause surface flaws, internal shrink cavities or blow holes in the casting.

OBJECTS It is an object of my invention to overcome or reduce the deficiencies of the presently used die casting die release materials or lubricants.

It is a further object to provide a die release material or lubricant that will withstand high temperatures without undue deterioration.

Another object is to provide a coating for the working faces of die casting dies and their shaping components that will act as a lubricant at elevated temperatures.

Another object is to provide a thin coating for die casting dies and their shaping components that will pre? I vent wetting or soldering or erosion by the molten metal being cast.

Other objects will be apparent from the following Description.

DESCRIPTION ln accordance with the present invention, a thin layer or coating of rare earth halide is applied to the surfaces of shaping members such as die casting dies and'their components such as core pins, gates, runners, sprues,

' etc., where the molten metal or alloy being cast isin contact with such surfaces.

The mold release or lubricant of the present invention is made of a rare earth halide material. Thus, any of the rare earth materials having an atomic number between 57 and 71 may be utilized, either singly or in combination.

Preferably, however, therare earth metal is combined with a fluoride. Most preferably, the rare earth fluorides are selected from cerium'fluoride and lanthanum fluoride and mixtures thereof and optionallyv including one or more of the remaining rare earthifluorides.

More specifically, the preferred rare earth fluorides are cerium fluoride (CeF lanthanum fluoride (LaF and/or mixtures thereof.

The coating may be applied inany convenient form including sheet, strip, or powderform.

It should be noted that the high-melting point of rare earth fluoride (for example cerium fluoride melts at a temperature of about l,324 C) makes them particularly suitable for this application. Furthermore, rare earth fluorides do not wet shaping members normally used in die casting. 4

Additionally, the rare earth fluoride may be diluted with inert diluents. However, at least 50 percent by weight of the mold release should be made up of rare earth halides. Exemplary diluent materials include: water, liquid silicone or glue.

The mold release of the present invention may be used in shaping members made of steel including carbon steel and low alloy steel containing minor amounts of such additives as chromium, vanadium, molybdenum, tungsten, silicon and manganese. Furthermore, the mold release may be used in shaping members made of tungsten base materials. Forexample the shaping members may be made of tungsten alone or tungsten alloys containing such additives as nickel in an amount of about 1 to 12 percent and iron in about 0.5 to 8 percent as is disclosed more fully in my patent application Ser. No. 855,713, filed Sept. 15, 1969. Additionally, tungsten-nickel-iron-molybdenum base shaping may be utilized as arev described in greater detail in my Application Ser. No. 855,701, filed Sept. 5, 1969,

now US. Pat. No. 3,656,731. In this eventuality the previously mentioned amounts of nickel and iron are generally used together with about 0.5 to about8 percent molybdenum.

Additionally, the mold release of the presentinvention may be utilized in connection with molybdenum and molybdenum base alloy shapingmembers. Since molybdenum has a density of approximately half that of tungsten, on a weight basis, molybdenum may often be less expensive material than tungsten base materials. For example, liquid phase sintered shaping, members may be utilized as described more fully in my Application Ser. No.- 790,861, now US. Pat. No. 3,720,990, filed Jan. 13, 1969. In this application awide variety of molybdenumbase compositions are disclosed which result in a liquid phase sintered matrix.

Furthermore, molybdenum base alloys containing carbide formers such as hafnium, zirconium, titanium, tantalum and/or columbium may be utilizedas is disclosed more fully in my Application Ser. No. 74,660, filed Sept. 23, 1970 and now abandoned.

The mold release of the present invention may be utilized in the casting of both ferrous and non-ferrous metals. For example, the mold release may be used in connection with the casting of copper and copper base alloys including brasses, bronzes, cupro-nickels, precipitation hardening copper base alloys having additives such as chromium, beryllium and zirconium, and dispersion hardened copper base alloys. Likewise, the mold release material may be utilized in the connection with the casting of aluminum and aluminum base materials, there being no particular restriction as to the composition of the aluminum base material and nearly all of the Aluminum Association alloys can be cast with less difficulty. Descriptions of the casting of aluminum and aluminum base alloys are given for example in the ASM Metals Handbook. Obviously, zinc and zinc base alloys, magnesium and magnesium base alloys, and other non-ferrous metals may be likewise east.

Similarly, ferrous base materials may be cast including the conventional cast iron material having carbon contents up to 3.5 percent and higher. Similarly, steel may be cast utilizing carbon contents up to 1 percent and higher. Similarly, alloy steels may be cast containing manganese, silicon and hardening elements such as chromium, vanadium, zirconium, tantalum and tungsten to the extent that such material can be presently cast with existing shaping members. For example, consideration will have to be given to the melting point of materials being cast when steel shaping members are utilized. However, the previously mentioned iron base compositions and others can readily be cast with the higher melting point tungsten, tungsten base alloys, molybdenum and molybdenum base alloys.

The mold release of the present invention may be applied to the shaping members periodically when the casting machine is not being operated. Alternatively, suitable means may be provided to spray the shaping members during operation between shots, when the movable member is at least partially apart from the fixed member after the casting has been, or is being, removed. Those skilled in the design of die casting apparatus will have no difficulty in arriving at suitable apparatus modifications to accomodate the foregoing.

I claim:

1. A method of die casting a metal which comprises applying a rare earth based lubricant selected from the group consisting of cerium tri-fluoride and lanthanum tri-fluoride to the surface of a die casting mold and die casting the metal.

2. The method according to claim 1 wherein the lubricant is cerium tri-fluoride.

3. The method according to claim 1 wherein the lubricant is lanthanum tri-fluoride. 

2. The method according to claim 1 wherein the lubricant is cerium tri-fluoride.
 3. The method according to claim 1 wherein the lubricant is lanthanum tri-fluoride. 